<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .box{
            width: 60%;
            height: 1000px;
            border: 1px black solid;
            margin: auto;
        }
        .box1{
            width: 600px;
            height: 300px;
            border: 1px black solid;
            margin: auto;
        }
        .box2{
            width: 600px;
            height: 300px;
            margin: auto;
            margin-top: 30px;
            border: 1px black solid;
        }
        .box3{
            width: 100px;
            height: 50px;
            margin: auto;
            margin-top: 30px;
            /* border: 1px black solid; */
        }
        button{
            width: 100px;
            height: 50px;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="box1"></div>
        <div class="box2"></div>
        <div class="box3">
            <button>发送</button>
        </div>
    </div>
</body>
</html>